Information technology (IT) adoption research recognizes theoretical limitations in discerning if and when user behavior results from perceived external influences or from personal volition. A clear understanding of this issue requires a precise distinction between mandatory and volitional behaviors. Consistent with organismic integration theory (OIT), this study situates the locus of user motivations inside the user. Drawing upon an endogenous view of behaviors, this research makes three key contributions. First, it develops the theoretical basis for clearly discerning if and when behavior results from perceived external influences or from personal volition. Specifically, it examines how endogenous psychological feelings of autonomy, freedom, conflict, and external pressure can predict and explain user intentions. Second, it proposes that behavior may result from combinations of perceived external influences and personal volition. Recognizing how such "collections of motivations" together influence behavior advances our understanding beyond the "dichotomy" of extrinsic versus intrinsic motivations often adopted in prior research. Third, it proposes that some desired behaviors may be thwarted or impeded by a conflict between perceived external influences and personal volition. The theoretically grounded research model was empirically validated in a field study on Blackboard, a Web-based education platform at a large university. Data collected from a sample of 211 users were tested using structural equation models of initial system adoption and experienced use. Empirical support was found for the proposed model and related hypotheses. The results of this study advance our understanding about user motivations for adopting IT.